Minimally Invasive Parathyroidectomy (MIP) is a surgical procedure to remove overactive parathyroid glands. These glands play a role in regulating the body's calcium levels, mainly by releasing or reabsorbing calcium into the bones. The parathyroid glands are very small, each about the size of a grain of rice, measuring approximately 4 mm. They are located behind and adjacent to the thyroid gland, and they appear yellowish-orange, unlike regular fat, which is yellow.
The primary reason for performing surgery on a parathyroid gland is the excessive secretion of hormones caused by benign growths. Usually, a single enlarged gland is involved, but in some cases, there may be two or more enlarged glands. Rarely, there are inherited syndromes that involve enlargement of one or more of the parathyroid glands. However, it is extremely rare for parathyroid cancer to develop. Secondary and tertiary hyperparathyroidism are extreme cases where all the parathyroid glands become overactive due to prolonged kidney failure.
The diagnosis of parathyroid gland overactivity is made by testing blood calcium and parathyroid hormone (PTH) levels. If both blood calcium and PTH levels are elevated above normal, then the patient is diagnosed with hyperparathyroidism. Additional tests may include measuring calcium in the urine and assessing bone density (osteoporosis).
Not every patient with elevated blood calcium levels requires surgery to remove the parathyroid gland. Nowadays, elevated blood calcium levels are often an incidental finding in routine blood tests. Clear indications for surgery and the decision to proceed with the operation are usually made through a collaboration between the surgeon and the endocrinologist.
Tests to locate the affected parathyroid gland before surgery include ultrasonography, nuclear medicine imaging with radioactive material, combined single-photon emission computed tomography (SPECT) imaging, and a 4-phase CT scan.
During the surgery, a quick hormone test is performed, and the affected parathyroid glands are identified using radioactive tracer material. After injection of the tracer into the patient's vein, it concentrates in the diseased gland, which can be detected with a Geiger counter. A small incision is made over the affected gland, and its removal is confirmed by checking the hormone level (PTH) before and after removal to ensure the correct gland was excised. If the PTH level does not drop to normal after removal, it may be necessary to expand the surgery (returning to conventional open surgery) to search for additional enlarged glands until the PTH level returns to normal.
Complications of the surgery may include damage to nerves (resulting in voice quality changes) which is very rare and usually recovers within 3 months. Other possible complications include surgical failure (in which no enlarged gland is found, occurring in about 5% of open surgeries and 2% of minimally invasive surgeries) and recurrence of overactivity due to the remaining glands.
The hospitalization process for minimally invasive parathyroidectomy involves pre-admission the evening before the surgery. On the morning of the surgery, the patient is taken to the nuclear medicine department for injection of a radioactive tracer, which is used to locate the affected parathyroid gland during surgery. After about 2-3 hours, the patient is taken to the operating room. In some cases, an ultrasound is performed during surgery to locate the diseased gland. After the surgery and an hour of recovery, the patient is taken back to the hospital room. Most patients are discharged the day after the surgery and return for a follow-up visit after about two weeks to check blood calcium and PTH levels and ensure the success of the operation. The incision is closed with dissolvable stitches, so there is no need to remove them later. There are no activity or dietary restrictions after this surgery.